Alistair Darling, the former Labour chancellor who is leading the campaign against Scottish independence, has taunted Alex Salmond for assuring people "everything will change but nothing will change".

He mocked the leader of the Scottish National party, who is expected to call a referendum on leaving the UK in 2014, for saying Scots would still be British even after they had left the union.

"He is saying we will keep the pound, be in a currency union with the rest of the United Kingdom, by the way not asking the rest of the UK whether they want that, and entering into the sort of currency union you have got in the eurozone right now," Darling, the leader of the Better Together campaign, told BBC Radio 4's Today programme on Monday.

"My argument is why on earth would you want to do that when everybody knows currency union inevitably takes you to closer economic and fiscal union? In other words you end up where you started," said Darling. "To argue in some way it is not going to change anything at all, well, what is the point of it?"

Darling, who was preparing to launch the pro-union campaign in Edinburgh, said Salmond no longer talked of the euro because he knew it was "toxic". The Scottish first minister had pointed to the success of other countries, but said: "I think you will find Ireland and Iceland [which] he used to compare us with, are now off the list."

Leaving the UK would leave Scotland "heavily dependent and exposed to the fortunes of North Sea oil", said Darling.

He insisted those fighting independence would remain positive about the benefits of "family and friendships", trade and the economy and the sharing of economic and cultural institutions that "bind us together".

The campaign has engaged media strategists Blue State Digital, which helped bring Barack Obama and the French president, François Hollande, to power, to build a website and oversee its online strategy.

Better Together will also distribute 500,000 leaflets, which will highlight the one in five workers in Scotland employed by English firms, and those working for the UK government in places such as the Department for International Development offices in East Kilbride. They will also point to the 800,000 Scots who live and work in England and Wales "without the need for papers or passports".

The campaign will be running full-page adverts in Scottish newspapers bearing the slogan "We want the best of both worlds", advocating support for a distinctive Scottish parliament and the strength of the UK through devolution.

A series of 10 leaflets will be produced looking at different areas in which Scotland benefits from being part of the UK.